NAD C 298 Power Amplifier With Purifi Eigentakt Amplification

[Tovarich007]

Let me add this:
The NAD C 298 is drab like a marble funeral urn. I just got a used on and it was scuffed along the top front edge. I sanded that edge carefully in preparation of repainting it to cover the scuffing. Right now the top edge is bare metal--a fine edge of bare metal, maybe one-eight inch of bare metal on the vertical front, and one-eighth inch along the adjoining horizontal top front, all across the front top. That little bit of exposed metal makes the entire front of the NAD C 298 much more attractive. It gives the box spatial definition. It works and it is a subtle change. See photos...there's a bright metal edge to the top of the NAD amp.

Why not. it's a matter of taste.
Classic NAD style is quite austere indeed, I like that personnaly.

 

[ebslo]

I just got a brand new NAD C 298 unit. I am very pleased with the sound, it's a big upgrade from my previous amp.

The speakers are super silent with this amp attached, no noise in the audio-section at all. However my unit's power supply also makes this humming sound. You can clearly hear it even 5 feet away. I think this is the same thing that others have observed as well. To be clear: this noise does not come from the speakers, it comes from the unit itself (probably the power supply).

So the big question is: there were other people in this thread talking about having their unit serviced because of the buzzing/humming sound. How did this turn out? Has it actually been fixed?

Note: My unit's firmware is v3.4, so I guess this is a pretty new batch.

I returned mine for exchange. My replacement unit is silent; not everyone was so lucky.

 

[Hov]

Anyone know if the heatsinks are just directly screwed into the bottom of the case using these holes (assuming they're mirrored on the bottom and threaded there but not sure).

Also curious about the type of metal they're using for the AC shielding and if there is a practical reason/advantage assuming the SMPS is well-designed and implemented.

Thanks!

 

[jasoncd]

Yes it's happened twice that I recall the past three months. Not a big annoyance when it's pretty rare, but doesn't fill me with confidence either.

Auto sense at times failed to turn on the left channel with my C298. Not a huge deal, it was fairly rare. Last week though my left channel cut out while the amp was still on. Power cycling fixed it.

It happened a few more times from last week. And today the left channel stopped working multiple times, and it would take multiple power cycles to get it working. Then it would fail again within a few minutes.

I think it's RIP for the NAD here.

 

[Angsty]

I think it's RIP for the NAD here.

If it is out of warranty, contact Peter Williams at Quirk Audio to see if he can help. He’s an NAD repair expert.

 

[arn]

Auto sense at times failed to turn on the left channel with my C298. Not a huge deal, it was fairly rare. Last week though my left channel cut out while the amp was still on. Power cycling fixed it.

It happened a few more times from last week. And today the left channel stopped working multiple times, and it would take multiple power cycles to get it working. Then it would fail again within a few minutes.

I think it's RIP for the NAD here.

I found, it is related with the input level.

 

[sadoMasupilami]

Auto sense at times failed to turn on the left channel with my C298. Not a huge deal, it was fairly rare. Last week though my left channel cut out while the amp was still on. Power cycling fixed it.

It happened a few more times from last week. And today the left channel stopped working multiple times, and it would take multiple power cycles to get it working. Then it would fail again within a few minutes.

I think it's RIP for the NAD here.

I had that once but it did not happen a second time. I really hope it will not happen again. If that is the case I will try changing sensing level.

Mine also has some whining from the device but only if I am with my ear directly above the enclosure. I am a little bit bothered by that but I’m reality it is not audible from where I am listening. I bought it because I got a good deal on a half year old unit.

 

[jasoncd]

If it is out of warranty, contact Peter Williams at Quirk Audio to see if he can help. He’s an NAD repair expert.

It is 2 months out of warranty, and I appreciate the advice.

To be clear for everyone, my left channel started to stop working even with auto sense off. A power cycle would get the left channel working again...but then the left channel has been stopping more and more often. And power cycling fixing the issue less and less.

Its unplugged now, I will try it again this weekend, maybe try RCA instead of XLR or anything else I can think of.

 

[eduardw]

make sure it is not your pre, you could swap the left and right inputs.

 

[pablolie]

i think NAD's power saving implementation is a bit questionable and may impact reliability long term. i had to get my M22 fixed once. when i got it back i disabled all power saving features, and it's been reliable since. ...oh and that touch button implementation is pure on-off roulette

 

[Kal Rubinson]

i think NAD's power saving implementation is a bit questionable and may impact reliability long term. i had to get my M22 fixed once. when i got it back i disabled all power saving features, and it's been reliable since. ...oh and that touch button implementation is pure on-off roulette

Agreed. I killed the touch button on the first NAD I reviewed and, in general, I prefer manual on-off implemented by 12v trigger.

 

[Angsty]

I found, it is related with the input level.

It can be modified with a change of resistor. Quirk Audio did a mod for my C272 and it functioned well afterward.

 

[vermouth]

After the audio shop telling me the product was out of warranty (they pulled up the wrong online order and started the RMA for the wrong product) they have now taking it back for analaysis. I am hoping they will honour the 2yr warranty as the RMA was raised in the time period.

Did anyone with a repaired or service C298 ever find out what was wrong with it? Did the same unit come back repaired? Was it fixed through firmware?

The engineer said that they sometimes just put varnish on noisy components...is that a thing?

Fingers crossed.

 

[vermouth]

From the repair centre.

"After assessment our engineer has filled the choke in the PSU with a sealant as per the service bulletin provided by NAD. He did remark that your C298 was one of the worst we’ve seen for this problem, and likely was manufactured before they started using silicone on this part during assembly. There will be nothing to pay for this service."

Being posted back so we'll see if it worked.

 

[vermouth]

a follow on email from the repair centre..."As suggested earlier I don’t think you can completely eliminate the noise due to the nature of the power supply, but it’s significantly dampened by the sealant so should no longer be audible outside of very quiet environments."

How does signal to noise ratio effect a product if there is physical noise?

 

[pogo]

How does signal to noise ratio effect a product if there is physical noise?

Noise is always physical. There is also a real world that plays a role and does not end at an amplifier output

 

[vermouth]

It's back from being repaired. It is dead silent from listening position, if you get within a few inches/or press your ear to the unit there is still an oscillating/hum.

But it is much better than before. I can for sure live with it!.

Can anyone else who has one put their ear to it and see if there has this now small issue.

 

[MaxBuck]

It's back from being repaired. It is dead silent from listening position, if you get within a few inches/or press your ear to the unit there is still an oscillating/hum.

But it is much better than before. I can for sure live with it!.

Can anyone else who has one put their ear to it and see if there has this now small issue.

I hear absolutely no hum when mine is operational.

 

[eduardw]

It's back from being repaired. It is dead silent from listening position, if you get within a few inches/or press your ear to the unit there is still an oscillating/hum.

But it is much better than before. I can for sure live with it!.

Can anyone else who has one put their ear to it and see if there has this now small issue.

From very close my two nad also make a very slight hum. Speakers are dead silent.

 

[MichaelEA]

Reading here all the quality problems with the C298, I'm dissapointed that NAD haven't improved! Many years ago I bought one of their large T753 receivers. It ended up back for repairs a few times until they gave up and offered to replace it with a newer model T765 (plus a small upgrade charge). The T765 then slowly developed cooling fan problems - the bearings failed and the fans would rattle horrible. I've slowly been disconnecting the fans and it's down to (I think) 2 out 4, but I don't drive the amp hard so I'm crossing fingers it's ok.